The prior art is replete with structures relating to perineal protective devices including such items as garment shields, drip containment or dribble cups, sanitary napkins, diapers, incontinent pads and the like. Such devices range from very thin material for protecting against garment stains which might otherwise result from small amounts of involuntary fluid discharge, to pads having sufficient capacity to absorb the full flow of menstrual fluid discharge, to still heavier pads for infant diapering and for collecting, absorbing and retaining the entire discharge of adult incontinence.
Particular shapes have been devised in an attempt to obtain good body conformance, leakage prevention, and comfort. While many are designed for re-use and are made from launderable fabrics, the most recent developments have been directed to disposable materials including non-woven webs, thin plastic films, and thick pads of absorbent fibers, in particular air-formed pads of wood cellulose fibers. A major difficulty with most of the disposable materials is that they do not have the drapability of more permanent cloth-like material and therefore will not conform well to the body, especially when made thick enough to provide the absorbent capacity needed for catamenial and diapering uses.
Various attempts have been made to obtain conformity by selecting particular geometries. While many of these obtain a good fit when first applied, they do not have the ability to move with changing body configurations. As a result, the material located between the thighs is often crushed by leg pressure soon after application, and thereby loses its initial conformance, resulting in gaps between the protective device and the body, or causing discomfort because of rubbing and/or chafing contact between the device and the body.
U.S. Pat. No. 4,067,336, to Russell L. Johnson, and assigned to the same assignee as the present invention, discloses a perineal protective device made from flexible sheet material which when folded on a set of pre-established lines assumes a self-adjusting, body-conforming shape, achieving improved comfort and containment characteristics while being well-suited for all size devices ranging from the above-mentioned relatively thin garment protectors to absorbent pads which handle full-discharge incontinents.
The protective device disclosed by Johnson comprises a sheet of flexible material of generally rectangular form adapted for folding on a set of pre-established fold lines. The sheet material is generally defined by a top body-contacting surface, a bottom surface, a front edge, a back edge, and two side edges. The pre-established fold lines along which the sheet material is folded prior to use comprise: (a) a main fold line centrally and longitudinally disposed along the major axis of the sheet and extending the full length of the sheet; (b) a first pair of rearwardly directed diverging fold lines originating on the main fold line from a common base point spaced inwardly from the front edge of the sheet, and extending to the sheet perimeter; and (c) a second pair of rearwardly directed diverging fold lines disposed between the first pair of diverging lines and the side edges of the sheet, with the second pair of lines also originating at the same common base point on the main fold line as the first set of lines and extending to the sheet perimeter.
The sheet material is adapted for inward folding on the main fold line, outward folding on the first pair of rearwardly diverging lines, and inward folding on the second pair of rearwardly diverging lines. When folded in this way, the sheet material has an upwardly concave or bent configuration in both the transverse and longitudinal directions. The deepest part or the greatest depth of the concavity in both directions originates at the common base point on the main fold line.
Johnson teaches that the manufacturer may either prefold the sheet material or simply prepare it for folding by the consumer just prior to use. Experience has shown that, in the interest of consumer convenience, it is preferable for the manufacturer to fold the device. Unfortunately, this specific fold has proven to be relatively difficult to perform in large scale production. In particular, because this fold is nonsymmetrical about its lateral axis, and because the material of the pad can be relatively thick, conventional automated folding apparatus have been unsatisfactory. Likewise, manual folding is undesirable because of the need for sterility and the higher costs involved.
In the interest of cost efficiency, disposable articles such as these are typically produced on a fully automated assembly line which necessarily moves at high speeds. It is thus desirable for the folding process to likewise be fully automated and also to be performed at rates at least as high as the rest of the assembly line.